sedimentary
Red Sandstone (Iron-rich)
Ferruginous Sandstone (variable formula, primarily SiO2 + Fe2O3)
Hardness: 6-7 (Mohs scale), Color: Red to reddish-brown, Luster: Dull/Earthy, Crystal structure: Granular/Clastic, Cleavage: None, Specific gravity: 2.2-2.8
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Red to reddish-brown, Luster: Dull/Earthy, Crystal structure: Granular/Clastic, Cleavage: None, Specific gravity: 2.2-2.8
Formation & geological history
Formed through the accumulation and cementation of sand-sized grains (mostly quartz) in arid desert environments or river basins; the red color is due to the oxidation of iron minerals (hematite). Generally spans from the Paleozoic to the Mesozoic eras.
Uses & applications
Used widely in construction for building facades, paving, and decorative garden mulch (red rock). High-quality blocks are used in historical architecture.
Geological facts
Famous for creating the iconic landscapes of the American Southwest, such as the Grand Canyon and Red Rocks Park in Colorado. The red hue is essentially 'rusting' on a geological scale.
Field identification & locations
Identify by its gritty texture (feels like sandpaper) and distinct red staining that may rub off slightly when wet. Commonly found in exposed desert plateaus and sedimentary basins.
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